What are the anatomical, physiological, and cellular mechanisms?

What is the physiological mechanisms by which O2 and CO2 may control ventilation?

• Answer:

  Mechanism of action The main stimulant for the central chemoreceptors is the increased hydrogen ion concentration. However, if the hydrogen ion concentration increases in blood, it cannot stimulate the central chemoreceptors because, the hydrogen ion from the blood cannot cross the blood brain barrier. On the other hand, if CO2 increases in the blood, it can easily cross the blood brain barrier and blood cerebrospinal fluid barrier and enter the interstitial fluid of brain or the cerebrospinal fluid. There the CO2 molecules combine with water to form carbonic acid. Since carbonic acid is unstable, it immediately dissociates into hydrogen ion and bicarbonate ion. CO2 +H20 --> H2CO3 --> H+ + HCO3- The hydrogen ion now stimulate the central chemoreceptors. The chemoreceptors send stimulatory impulses to inspiratory center causing increased rate and force of breathing. Because of this, the excess CO2 is washed out and the respiration is brought back to normal. Lack of oxygen does not have any significant effect on the central chemoreceptors except that it generally depresses the overall function of the brain. hope this had helped u..gud luck. =)